[ARDF] AM A2A Modulation...

[Matthew Robbins]

Bruce (and all),

    My comment about a non-PicCon Pic was basically asking the
question, "If you are making an ARDF 2m transmitter (from whole
cloth), first, how do you achieve A2A modulation, and second, does the
easy availablility of a programmable audio source for a DTMF-like tone
change any assumptions about ARDF transmitter design---Since you need
a controller anyway, and you're likely to use a Pic, would an SSB
radio design have advantages over existing 2m ARDF transmitters.  In
the whole e-mail, I guess I was mixing together two thoughts---First
about a quick way to practice using a multimode rig, and second about
designing ARDF 2m transmitters.

    How do you look at a 2m transmitter output?  Are there
oscilloscopes that will go that fast, or do you need something like an
LO and a mixer?  An HT I was using right next to the antenna (with at
least 35W out) had little squelch tails after the dits and dahs,
although it couldn't keep up with the dits.  I figured that was
showing very low residual signal during the audio null, but I really
have no idea what the signal was doing in those nulls.

    It certainly sounds like the existing ways of achieving A2A (as
described by Dale) are simpler than an SSB design transmitter.

    My interest in A2A is primarily because I've hunted it, and it's a
lot harder than FM MCW.  I want to practice before I have to hunt it
in a big competition.

Matthew
AA9YH
Cincinnati